Telegraphy.



No. 707,959. Patented Aug. 26; I902.

A. C. CREHURE.

TELEGRAPHY.

(Application filed Oct. 21, 1901.)

5 Sheets-Sheet 1.

(No Model.)

00-. MTQ-LITNO, wumuama. n. c.

No. 707,959. Patented Aug. 26, I902.

A. D. CREHORE.

TELEGRAPHY.

Application filed Out. 21, 1901.)

(No Medal.) I 5 Sheets-Sheet 2.

Patented Aug. 26, 1902.

A. 'C. CBEHORE.

TELEGRAPHY. (Application filed 00!. 2] I901.-

KNO Model.)

5 Sheets-Sheet 3.

Mo WASHINGTON. 0. c4

No. 707,959. Patented Aug. 26, I902.

A. C. CHEHURE. TELEGRAPHY.

(Application filed Oct. 21, 1901.)

(No Model.) 5 Sheeis Sheet 4 m: NORRIS vzvzns co, woTo-Lrruu. wumuofomD. c

v Patented Aug. 26, I902. A. C. CREHORE.

TELEGBAPHY.

(Application filed Oct. 21, 1901.;

5 Sheets-Sheet 5 (No Model.)

rm: NQRRIS versus no. mo'muma. wasmn NIIIZD STATES PATENT ()FFTCE.

ALBERT O. CREIIORE, OF TARRYTOWN, NEW YORK.

TELEG RAPHY.

SPECIFICATION forming part of Letters Patent No. 707,959, dated August26, 1902.

Application filed October 21,1901. 'Serial No. 79,385. (No model.)

To (0 whom it may concern.-

Be it known that I, ALBERT O. CREHORE, a citizen of the United States,and a resident of Tarrytown, in the county of Westchester and State ofNew York, have invented certain new and useful Improvements inTelegraphy, of which the following is a specification.

My invention relates to that class of telegraph apparatus known assuperposed-current systems, wherein one class or set of messages orsignals is sent over a wire by the use of momentary currents of shortduration and sharply defined or having a high rate of change ofelectromotive force, While another set of signals or messages is sentover the same wire or circuit by currents of longer duration or having alower rate of change and upon which the momentary currents aresuperposed. In the following description the momentary currents will bedesignated as pulsatory currents, and the telegraph apparatus operatedthereby will be called the pulsatory-current side of the systein,whilethe transmission and reception of messages efiected by the use of thecurrents of longer duration will be described as effected by the use ofcontinuous currents, and the apparatns using the continuous current willbe called the continuous-current side of the system. For the purpose ofillustrating the invention it will be assumed that the signals sent bythe pulsatory currents are each produced bya succession of such'currentsflowing continuously or uninterruptedly for a period of timecorresponding to the duration of the signal to be produced, although, aswell understood in the art, each signal might be sent by two pulses onlyand separated by an interval of greater or less duration, during whichany change of electric condition takes place on the circuit. In thisclass of telegraphs it has been proposed to employ condenser-shuntscontaining the pulsatory-current receivers and formed aroundra suitablereactance or inductance, the latter permitting the flow of thecontinuous currents but obstructing the how of the pulsatory currents,while the condenser, on the other hand, affords a path for the pulsatorycurrents but cuts off the flow of the continuous current. On the otherhand, the pulsatory currents are ordinarily prevented from acting uponthe continuous-current receiver by shunting such pulsatory currentsthrough a suitable condenser and by the reactance or inductance in thebranch containing said receiver. In most cases the transmitter forthecontinuouscurrent side of the system has beenincluded in the branch withthe continuous-current receiver, which, as stated, is shunted by acondenser.

The objects of my invention are in general to avoid the disturbance orkick in the receiving instrument due to the discharge of the condenseror to the operation of any of the keys or transmitters in the system,and also to so arrange the receivers for the pulsatory and continuoussides of the system respectively with relation to one another and to thetransmitters for the two sides of the system that they shall afford aminimum impedance to the flow of pulsatory current.

To these ends my invention consists,firstly, in the combination, withthe continuous-current receivers and their condenser-shunts, ofprotective non-inductive shunts properly adjusted to afiord a ready pathfor any discharge current from said condenser following the charge ofthe same, either by the pulsatory currents or by the continuouscurrents. By the use of this appliance I not only avoid any kick in thecontinuous-current receiver, but especially adapt the system to use forWay-station Work with a large number of stations, inasmuch as thenon-inductive shunt materially lessens the total resistance of thestation apparatus to the flow of the pulsatory current and permits alarge number of stations to be employed without requiring an electromotive force in the pulsatory-current generator of'prohibitive amount.Inasmuch as the flow of alternating current/upon a circuit diminisheswith the distance from the pulsating-current generator, I am enabled tosacrifice operating-current for those pulsatingcurrent receivers whichare at the end of the line nearest the generator and where owing to thestatic capacity of the line the pulsating currentis large and allow itto pass down to the more remote stations, where it would be otherwisesmall, owing to the absorbing capacity of the line at the portion nearerthe pulsating-generator. Hence the line maybe operated with a largernumber of way-station apparatus or with a. less strength of alternatingcurrent.

Another part of my invention consists in arranging the receivers for thepulsatory-current and continuous-current sides of the system in shunt toone another, the shunt or branch for the pulsatory-current receiverbeing made to include a condenser, and both shunts being free of thetransmitting devices, which being placed at another point on the circuitdo not cause any kick in the receivers through the opening and closingof the circuit for the condenser in the branch containing thepulsatory-current receiver.

Myinventionconsists,further,in the combination, With thepulsatory-current receiver and continuous-current receiverin shuntrelation to one another on the circuit, of a condenser in thepulsatory-current branch and a non-inductive resistance in a shuntaround the continuous-current receiver. By thus arranging the receivingapparatus at any way-station when the station is not in use fortransmitting messages I very materially reduce the total resistance ofthe circuit to the flow of the alternating or pulsatory currents, andthus very greatly increase the number of way-stations that may beoperated upon a circuit and for any given line reduce the strength ofalternating current which it is necessary to use. It is Well recognizedthat the difiiculty in operating a telegraph-line, especially whenemploying an alternating current, assuming that the insulationresistance is high, increases as the product of the resistance and thedistributed electrical capacity increases. It does not make so muchdifference how these two quantities are proportioned, provided Weconsider their product. For simplicity, consider the case of a linehaving only two stations, one at each terminal, equipped fordupleX-diplex working. The eifect of the distributed capacity is tocause the alternating current to decrease rapidly as we proceed from thetransmitting toward the receiving end of the line. To maintain a fixedcurrent at the receiver, which is that required to operate it, it is necessary to employ currents at the transmitting end, which become rapidlylarger as the product of the resistance and distributed capacity isincreased; but the larger the current the greater the disturbance byinduction upon neighboring telephone-lines, particularly at the end ofthe line where the generator is located, while, moreover, there isgreater liability to disturbance of the Morse side of the system fromthe action ofthe condensers used for the pulsatory-current side. If theattempt he made to overcome the difficulty by using lower frequencies,there is increased liability to disturbance between thetWo sides of thesystem itself, since the currents employed for the two sides of thesystem are then less fully differentiated. My invention overcomes thedifficulties by making it possible to work the system with a lessstrength of current than would otherwise be required.

In the accompanying drawings, Figure 1 illustrates diagrammatically anarrangement of apparatus embodying my invention and shows the inventionas carried out in a waystation system wherein the pulsating-currentgenerator is located at one point and the signals are transmitted overthe pulsatory-current side of the system from way-stations by suitablymodifying the electrical condition of the circuit as to the flow ofpulsating current. Fig. 2 illustrates the application of my invention toa way-station system wherein Waystations are provided withpulsatory-current generators introduced into the circuit for the purposeoftransmittingsignals. Fig. 3 shows another arrangement of thetransmitters adapted for use in connection with the arrangement ofreceivers and generators illustrated in Fig. 1. Fig. 4 illustrates amodification in the arrangement of the pulsatorycurrent generator andtransmitter at the terminal station. Fig. 5 illustrates a modificationof the arrangement of devices for transmitting on the pulsatory-currentside of the system, and Fig. 6 a modification 0f the arrangement ofapparatus for transmitting on the continuous-current side of the system.Fig. 7 shows in a simplified form the arrangement of Fig. 1 as itpractically exists when two stations are transmitting sim ultaneously,one by the continuous-current side andthe other by the pulsating-currentside, the parts which are short-circuited and which do not, therefore,offer any impedance being omitted from the diagram.

Referring to Fig. 1, I have shown the line provided with two terminalstations A WV and a number of intermediate stations B O U V. Myinvention is, however, adapted for use with a very much larger number ofintermediate stations, and I have in practice employed as many as twentyon the same circuit without difficulty. Inasmuch as one of the principaluses of my invention is upon circuits employing an ordinary Morsetelegraph apparatus operated by continuous currents, I have shown thecircuit as equipped with a Morse telegraph instrument of the usualcharacter for the continuous-current side of the system.

3 indicates the Morse relays, and 5 the continuous-current generatorssupplying the current for operating said relays. 1 indicates the Morsekeys controlling the flow of current from said generators in the usualWay over the circuit. For a closed-circuit system it will be understoodthat said keys are normally shunted by the usual circuit-closers 15 andthat the current from the generators 5 flows over the circuit andthrough all the receivers 3, but that by opening the circuitcloser 15for any key 1 a message may be transmitted by said key to be received onany or all of the Morse relays 3.

6 indicates the pulsating-current generator, which operates to keep theline continuously charged with pulsating current, preferably a sine-wavecurrent, for which purpose said generator 6 may be analternating-current dynamo constructed to supply approximately sine-wavecurrent. A pulsatory-current generator 6 is shown at each end of theline. In practice onlyone of them would be used at a time. The generator6 at station A is shown connected into circuit by the use of switchingappliances 24: of typical form, while the generator 6 at the oppositeend of the line is disconnected. Both generators 5 are shown connectedat opposite ends of the line by switches 25, although in way-stationwork the generator 5 at the same station with the pulsating-currentgenerator being used may be removed from the circuit, leaving thegenerator 6 only in circuit. For closed circuit working the pulsationsof the generator are permitted to normally flow over the whole circuitand through the apparatus at all of the stations. Any form oftransmitting apparatus for the pulsatory-current side of the system maybe used. In Fig. 1 the appara tus for this purpose consists oftransmitters 2, which operate to open and close a shunt formed around asuitable inductance 12 and containing a condenser 8. In Fig. 1 theinductance is in the branch or shunt containing the transmitter 1, butmight be in a shunt or branch independent of said transmitter, asindicated in Fig. 3, or in any other desired relation. The inductance 12may consist of a coil of wire wound on a core having a closed magneticcircuit, as indicated and as well understood in the art. The operationof the key 2 will alternately remove and insert the impedance orreactance afforded by this coil to the flow of pulsating currents,thereby causing the pulsating-current receiver to respond in thewell-known manner. The keys 2 are also provided with the usualcircuitclosers 15. In order that the impedance of the condenser andinductance used with the transmitting devices may be removed from thecircuit when the apparatus is not in use for transmitting messages, butonly for receiving, it is preferred to employ the shunting arrangementshown and consisting of the switch 15, that in addition to closing the.circuit around the contacts of keys 1 2 also operates to complete aconnection upon a supplemental contact 16. The contacts 16 beingconnected, as shown, and the devices arranged with relation to oneanother as indicated,it is obvious that when both switches are closed acomplete short circuit will be formed around the inductance 12 andcondenser 8 used in connection with keys 1 and 2. When, however, eitherswitch is opened, the key with which it is associated maybe employed inthe ordinary way, and if both be in use the closing of thecircuit-closer 15 associated with one key will not render the other keyinoperative. This special arrangement of devices is, however, claimed byme in the application in which I have set forth and claimed the specialarrangement of keys shown in this diagram.

4 indicates the pulsating-current receiver, which may be a short-coreneutral relay, as well understood in the art, but is preferably apolarized receiving instrument, for the reason that a polarizedreceiving instrument is more sensitive to pulsating currents. Eachreceiver 3 is shunted by a condenser 8, and the pulsating-currentreceiver 4 is preferably arranged in the same shunt with the condenser,as shown. In a shunt around the receiver 3 is a non-inductive resistance9 of such amount or value as to afford a ready path for thedischarge-currents from the con denser 8, thereby protecting theinstrument 3 from the disturbing effect of the condenserdischarges. Thisshunt I term a protective or compensating shunt. It is of comparativelylow resistance, as its function is not to open the line to the fiow ofthe continuous current. With a relay of three thousand ohms resistanceit might be of, say, four hundred ohms.

It will be noticed that the transmitters 1 are not in the shunt with thereceivers 3, but are at points on the circuit outside said shunt, sothat the instruments are less liable to disturbance upon the operationof the key and the discharge of the condenser in the shunt around it;also, the transmitter2 for the pulsatory-current side of the system isin a shunt or branch independent of the branches containing thereceiving instruments and for a similarpurpose. Thisarrangementisofgreatpracticalimportance, as it substantially eliminates the difficulties anddisturbances in the action of the relays which would arise from theoperation of the transmitters if the attempt be made to locate andoperate them in the same branches with their receivers, respectively.The non-inductive resistance 9 at those stations nearer thepulsatory-current generator 6 has a greater shunting efiect than thoseat stations more remote from the generator for the reason alreadystated-namely, that owing to the static capacity of the line and itspower to absorb the alternating current more current will flow on theportion of circuit near the generator, and there will be less effectfrom such current as the remote end of the line is approached. Sincethen the actual amount of pulsating current is greater at stationsnearer the generator, it is permissible to shunt current from thepulsating-current receivers at such stations and use the shunted currentto work the receivers more remote from the generator. By this means I amenabled to work the system with a larger number of way-stations and witha less electrornotive force of pulsating-current generator than would bethe case if the device 9 were not employed. This device I term aninductance-load or retardation-coil. The non-inductive shunt 9, adjustedto have the proper resistance forthe action described, will with thearrangement of receivers shown, wherein the receiver 3 is in shunt tothe condenser, have also the important function of diverting thedischarge from said condenser following the charge of the same by thecurrents used on the system and will therefore protect the receiver 3from disturbance. It will also protect said receiver 3 from the actionof any transitory or variable currents arising from condensers,inductances, or other sources outside the receiver by affording ashunt-path or path of comparatively low resistance for them. Thearrangement of the receivers in shunt relation to one another, asdescribed, also serves to decrease the resistance of the stationapparatus when not in use, and this resistance is further diminished bythe presence of the non-inductive shunt 9 in multiple-arc relation tothe other two branches containing the receivers 4 and 3. I claimherein,broad 1y,

as my invention this arrangement of the receivers in branches which areshunts to one another and which are independent of the portions ofcircuit containing the transmitters, as shown in Fig. 1, but do notlimit my self to the particular arrangement of the transmitters inbranches in shunt relation to one another, as shown in said figure,since the Value of the arrangementof the receivers may be realized withother arrangements of the transmitters-sucl1, for instance, as thearrangement shown in Fig. 3. I

The diagram Fig. 1 shows a line having two terminal and four waystations. The terminal stations are marked A and W, and the severalintermediate stations are marked B, O, U, and V. A larger number ofintermediate stations might be employed. Upon examination of the diagramit will be seen that the switch 15 for the continuous-current side ofthe system at station Vis opened and the switch 15 for thepulsatory-current side of the system at station A is also opened. At allother stations the switches 15 for both keys 1 2 are closed, and theimpedance afforded by the inductance 12 and condenser used in connectionwith the transmitters is removed from the circuit at said stations. Thereceivers 3 and 4, however, maintain their relation to the circuit, andeach will respond to its own proper character of current. The pulsatorycurrents controlled by the transmitter 2 at station A flow over thewhole circuit and operate all of the receivers 4 on the circuit,including that at station V, the action of the key being simply to openand close the shunt around the inductance 12 at station A and eachclosure allowing the pulsatory currents to flow freely over the circuitwithout encountering the impedance offered by the inductance l2. Saidpulsatory currents flowing down the line operate upon all the receivers4, even to the most distant. Similarly, any key 2 at any station may beemployed in transmitting the signals by the pulsatory-current side ofthe system to stain the simplified diagram Fig. 7. With a line having alarge number of stations equipped as shown it may not be found eX-pedient to transmit from station WV toward station A through any largenumber of stations by the use of the pulsatory currents generated at A.Under such circumstances and if it is desired to reach as far asstastation A on'the continuous-current side of the system to remove thegenerator 6 from connection with the line at station A, and the operatorat W may then switch in his generator 6 and by operating his key 2 willcause the pulsatory-current receivers at all the stations on the wholecircuit to respond, inasmuch as the flow of currents from said generatoris completely out off by the action of said key. Also, as will beobvious, the operator at any intermediate station between W and A maytransmit over the pulsatory-current side of the system effectually toall stations in the direction of station A in a similar way, thegenerator 6 having been connected at station W and that of A having beenremoved. If the station is near W, the operator may also transmit to Wand intermediate stations between his own station and W by modifying thepulsatory current of generator 6 at station W through opening andclosing the shunt around the inductance 12, as already explained.

I do not limit myself to placing the pulsatory-current generator atterminal stations on the circuit, as it may be placed at other pointsthereof and the flow of its current modified in the manner alreadydescribed by the action of the key 2.

While I have shown all of the stations similarly equipped in the diagramFig. 1, some intermediate stations might be provided with apparatusdesigned to work only on the continuous-current side of the system, asindicated at station 0 in Fig. 3 of the accompanying drawings.

The combination of the special arrangement of transmitters shown in Fig.1 with the special arrangement of receivers shown in the same figure isnot herein claimed, as it forms the subject of claims in anotherapplication for patent filed by me of even date herewith, Serial No.79,383.

The shunting non-inductive resistance 9, employed as described, isespecially valuable in connection with the relative arrangement of thereceivers shown in Fig. 1, but may also be employed with otherarrangements of said receivers-as, for instance, in arrangements wherethe two receivers are located in series relation to one another on thecircuit and the receiver 3 is shunted only by the resistance 9.

In the diagram Fig. 2 I have shown two terminal stations A NV and oneintermediate station U all provided with apparatus for telegraphing bothby continuous and pulsating current. At the terminal stations thetransmitting apparatus for the pulsatory-current side of the system maybe of any desired form, but is shown as comprising a key 2, controllingthe local circuit of a magnet,which operates upon a transmitter 2 of thecontinuity-preserving type and having its contacts connected, as shown,to the condenser in the shunt around the key 1 and to the pulsatinggenerator 6 in such manner that when the transmitter is opened thebranch containing the condenser is closed directly to the continuationof the circuit leading to the generator 5 and earth. When the key isclosed, the direct connection is broken and the generator 6 is includedin the branch with the condenser, so that the pulsatory currentgenerated thereby will be caused to flow upon the circuit and operateupon the receivers for the pulsatory current side of the system. Thetransmitter 1 for the continuous side of the system is in the branchwith the resistance 12, which latter operates to prevent the pulsatingcurrents in the generator 6 from flowing in short circuit when saidgenerator is connected into the condenser branch. The transmittingapparatus at station U is of similar character, so that when thetransmitter 2 is on its back stop the short circuit through thecondenser will be closed directly, but when on its front stop the directconnection formed over the back contact will be broken and a substituteconnection through the front contact, including the pulsatingcurrentgenerator 6, will be formed, so that the pulsating currents from thelatter will be supplied to the line and will affect all of thepulsatory-current receivers 4 on the circuit. A similar arrangement ofdevices to that shown in Fig. 1 may be employed for cutting out theimpedance of the condenser and inductance used in connection withthe.transmitting apparatus at the stations A U WV or any stationssimilarly equipped. The circuit-closing switches 15, by which this iseffected, are shown as used in connection with the transmitter 1 andwith the key 2, which controls the transmitter 2', and is connected in asimilar way to those shown in the diagram Fig. 1. Upon the closure ofboth circuit-closers 15 a shunt which short-circuits both the reactance12 and the condenser 8 is formed over the contacts 16 of thecircuitclosers.

Instead of connecting the generator 6 into circuit in the mannerindicated in Fig. 2 it might be arranged as shown in Fig. 4, so thatwhen the transmitter 2 is on its backstop a branch circuit from the mainline through the condenser is closed directly to earth; but when thetransmitter is on its front stop said direct connection is broken and aconnection substituted from said condenser through the pulsatory-currentgenerator, but not including the continuous current generator, as wouldbe the case with the arrangement shown in Fig. 2.

Other way-stations upon the circuit, Fig. 2, may obviously be providedwith continuouscurrent apparatusas, for instance, stations B, O, and V.In each of these cases an artificial shunt containing a condenser 8 andan inductance 12 is provided, said inductance taking the place of theinductance afforded by the receiver 4 at stations A U W and otherssimilarly equipped. The inductance 12 should be adjusted so as tobalance by its reactance the opposing reactance of the condenser and tothereby furnish at the stations B O V a ready path through said stationsfor the pulsatory current at all times. This inductance 12, as describedin another application for patent filed by me of even date herewith,Serial No. 79,387, wherein I claim the balancing of the condensercapacity or react-ance by the reactance of an inductance both arrangedin the shu nt to the continuouscurrent receiver 3, preferably consistsof a coil wound upon a core which has a magnetic circuit of ironcompletely closed, excepting at one or more points, where a narrow orthin break is afforded by an air-gap or similar break in the magneticcontinuity of the iron circuit. Said inductance might, however, be ofother form. The transmitter 1 at each of the way-stations operates tobreak and close the circuit for the continuous currents, while the shuntcontaining the condenser 8 affords at all times a path for the pulsatorycurrent. The non-inductive shunt 9 at said stations B O V has thefunction already described.

In Fig. 3 the arrangement of receivers herein claimed is shown asapplied on a circuit having a different arrangement of the transmitters.In this arrangement the line is shown provided with transmitting andreceiving apparatus for both the pulsatory and continuous current sideof the system at stations A, B, V, and W, A and W being terminalstations. One intermediate station G is shown provided with apparatusWorking on the continuous side of the system only, although a largernumber of stations like 0 or like 13 might be employed on the circuit.In general it is preferable to use at all stations equipped withpulsatory-current apparatus suitable continuous-current apparatus, alsoto permit the operator receiving on the pulsatory-current side to breakthe distant transmitting-station when the pulsatory-current generator isat some distance from the receiver-station, so as to make it diflicultto reach the transmitting-station on the pulsatory-current side byreason of the absorbing IIO capacity of the line for the pulsatorycurrents. In the diagram Fig. 3 the pulsatorycurrent generator furnishesto the Whole line a pulsatory electromotive force. Said generator mightbe, however, at some other station than station A. The transmitters forthe pulsatory and continuous current sides of the system are here shownas arranged in series relation to-one another instead of shunt relation.Each transmitter 1 for the continuouscurrent side of the system isadapted to make and break the shunt around a condenser 8, therebypractically opening and closing the circuitforthe continuous currents,while each transmitter 2 for the pulsatory-current side of the systemoperates to make and break a shunt around the inductance 12 of highreactance and low resistance, thereby throwing said reactance into andout of the circuit, so as to alternately permit the pulsatory currentsto flow and to stop their flow. This reactance ordinarily being of lowohmic resistance, permits the continuous current to flow readily. Incases where the circuit is short or the number of stations equipped withcontinuous-current apparatus is small the operation of the key 2, itconnected in a direct shunt across the terminals of the inductance 12,might by shunting the resistance of 12 produce a false signal in thecontinuous-current receivers 3. To obviate such disturbance upon thecontinuous-current side of the system through variations of impedanceintroduced by the action of the key 2, a condenser 8 may be included inthe shunt with it around the inductance, as shown in Fig. 5. The shunt,however, even with the condenser in circuit, will still allow thepulsatory ourrent to fiow when the key is closed, while the continuouscurrent will at all times'find a path through the coils of inductance12. Inasmuch as the shunt containing the key is at all times open to thecontinuous current through the presence of the condenser, no disturbingeffect upon the continuous-current side will be produced by theoperation of said key. In circuit with the condenser 8, placed in shuntto key 1, as shown in Fig. 3, there may be provided a reactance, asindicated, consisting of an inductance 12,adjusted to balance thereactance of the condenser 8, and therebypermit the pulsatory current toflow more .freely through said branch or shunt. For a reactance used inthis relation I prefer to employ the form which is described and claimedin another application for patent filed by me of even date herewith,Serial No. 79,387, and which in the shunt to the key has the additionalfunction of preventing sparking at the contacts of the key. Thereactance-coil is Wound upon a core whose magnetic circuit is closedexcepting for the presence of a narrow gap (indicated at 20) consistingofairorothernon-magnetic substance. When the total impedance of thecircuit to alternating currents is small, disturbance or change ofimpedance on the alternating-curing current is observed.

rent side of the system by working the key 1 may be avoided byintroducing a reactance 12 into the shunt or branch containing said key,asindicated in Fig. 6. This inductance should have a high reactance orimpedance and low ohmic resistance. It serves to block 01? the flow ofthe pulsatory currents through the shunt controlled by the transmitter 1effectually, so that the impedance to the fiow of the pulsatory currentsremains the same Whether the key be opened or closed in the operation oftransmitting a signal. Hence no disturbance in the impedance to the flowof said pulsatory currents at the transmitter occurs when the signalsare being transmitted on the continuous-current side. The ciruit-closer15 preferably in this case closes circuit upon a contact which isconnected to the front anvil of the keyand the inductance 12 remains incircuit when the key is out of,

use. When the Morse key is opened, the only remaining path for thealternating current is through the shunt. Sometimes there is no load orretardation coil required in series with the Morse key and in othercases it is required. If the line has a large number of stations withMorse relays, which are really equivalent to load-coils, and also hassmall distributed capacity, these coils are not required; but for thepresent purpose let us consider a two-station line only where thesecoils are used. It is very objectionable to have the working of theMorse key cause any effect upon the alternating-current relay in theline. It will do this (with a certain adjustment of the relay) if thevalue of the alternating current flowing is at all disturbed by theopening and closing of the key. For simplification suppose that there isno line between the terminal stations, but that the circuits have nobalancing-coils with the condenser around the keys. If an ammeter isplaced in the relay-circuit 4, the alternatingcurrent generator beingcontinuously in the line, the current in 4 will rise when 1 is openedand fall when 1 is closed, the generated electromotive force beingconstant. This result is surprising when first considered, as it isnatural to expect that the closing of the key reduces the totalimpedance bf the line, and thus increases the current in 4. When theproper coils are inserted in the condensershuntaround the keys 1, itwill be observed that when their inductance is larger than the propervalue the current in 4 rises upon closing the key 1 and falls uponopening it. This is exactly opposite from the previous effect before thecoils were inserted. It is evident,

therefore, that there must be some value for the inductance of thecoils, which will make it possible to operate the keys 1 without eitherincreasing or decreasing the current in the alternating-current relay.This is approximately the balancing value for the condenser and may bemost accurately obtained by adjusting until no effect on the alternat-It would be necessary to resort to vector diagrams, which obtain whensine-waves are employed, to explain this result.

With the arrangement shown in Fig. 3 the circuit-closer 15 for thepulsatory-current side of the system may be opened and the transmitter 1used for transmitting signals over the pulsatory-current side, asalready described, and simultaneously or not with the operation of thetransmitter 2 for the pulsatory-current side of the system at the samestation or at any other station, its switch for the circuit-closer15having been also opened. The receivers 3 and 4 for all stations on thecircuit will respond to the operation of said keys, as alreadyexplained. At the way-station C, where continuous-current apparatus onlyis shown, the receiver 3 has a shunting non-inductive resistance 9, anda shunt is provided which electrically is the same as the shuntcontaining the pulsatory-current receiver and condenser at otherstations. In the shunt at C the condenser Sis included in circuit with asuitable inductance 12, as already explained, which represents thereactance of the receiver; at other stations where receivers areprovided for both sides of the system. This inductance balances by itsreactance the reactance of the condenser 8 and assists the flow of thepulsatory currents through the station 0. The inductance,which ispreferably of the form already described as here used and as used in theshunts in connection with the transmitters 1 and 2, is claimed, broadly,in another application for patent filed by me of even dateherewitl1,Serial No. 79,387. The transmitter l at station G acts, asalready explained, to simply open and close the circuit to the flow ofthe continuous currents. The manner of transmitting by thepulsatory-current side through the operation of a key which shunts areactance or inductance and the system of way-station telegraphyillustrated in Figs. 1 and 3, involving the use of pulsatory-currentgenerators at terminals of the line, are not herein claimed, as theyform the subject of claims in my application for patent filed by me ofeven date herewith, Serial No. 79,384.

Myinvention is obviously applicable to systems wherein the transmittingappliances are arranged in still other ways and also as to some of itsfeatures to systems wherein the transmitters and receivers for the twosides of the system, respectively, are arranged in still other relationsto one another and to the circuit.

What I claim as my invention is 1. In a superposed-current telegraph,the combination with a continuous-current receiver and pulsating'currentreceiver in shunt relation to one another upon the main line asdescribed and having a condenser in the branch containing thepulsating-current receiver, of transmitters for the two sides of thesystem placed in branches or portions of the circuit independent of thebranches containing said receivers. V

2. In a superposed-current telegraph, the combination of acontinnous-current receiver in a shunt or branch of the main line, apulsatory-current receiver in a shunt or branch of the main line, acondenser in said mainline shunt, and a transmitting apparatus for thecontinuous-current side of'the system in a branch or portion of thecircuit outside of both receiver branches.

3. In a superposed-current telegraph, the combination substantially asdescribed upon the same line, of means for producing pulsatory currentsfor sending one class of signals over said line, pulsatory-currentreceivers for said signals, continuous-current receivers for thecontinuous-current side of the system, and branches around the coils ofsaid continuous-current receivers forming non-inductive shunts ofcomparatively low resistance, as and for the purpose described.

4. In a pulsatory -current telegraph, the combination of acontinuous-current receiver in a branch of the circuit continuallyclosed, a shunt to said receiver containing a pulsatory-current receiverand condenser, and a non-inductive resistance in multiple-arc relationto the branches of the circuit containing respectively saidpulsatory-current and continuous-current receivers.

5. In a superposed-current telegraph, the combination of apulsatory-current receiver and a continuous-current receiver in shuntrelation to one another, a condenser in the branch with thepulsatory-current receiver and a non-inductive resistance in a shuntaround the continuous-current receiver.

6. In a superposed-current telegraph, the combination with thecontinuous-current receivers, of non-inductive protective shuntsconnected directly around the receiver-coils and of comparatively lowresistance as described so as to protect the said receiver from thedisturbing action of pulsatory or variable currents and to. also permitthe system to be operated with pulsatory currents of comparatively smallstrength, as and for the purpose set forth.

7. In a superposed-current telegraph, the combination with thecontinuous-current receivers and their condenser-shunts for thepulsatory currents, of protective non-inductive shunts for saidcontinuous-current receivers adapted to shunt the condenser dischargeand to permit pulsatory current to flow down the line to the moredistant stations.

8. In a superposed-current telegraph, the combination with acontinuous-current receiver and a condenser in shunt to the same forforming a path around said receiver for the pulsatory-current side ofthe system, of a protective non-inductive shunt to said re: ceiveradapted to form a diverting path for the discharge of the condenserwhereby said receiver may be protected from disturbance from thecondenser discharge.

9. In a superposed-current system of telegraphy, receiving apparatus forthe continuous and pulsatory current sides of the system comprising apulsatory-current receiver and condenser in one branch of the circuit, adirect-current receiver in a branch forming a shunt to saidpulsatory-current receiver and condenser, and a compensating shuntaround the direct-current receiver adapted to afford a path fordiverting the dischargecurrents of the condenser around thesaiddirect-current receiver, as and for the purpose described. I

10. In a superposed-current telegraph, the combination with apulsatory-current generator adapted to generate electromotive force ofthe sine-wave type, a continuous-current receiver, a non-inductive shuntto said receiver, a continuous-current transmitter in the main lineoutside of the said shunt, and a shunt or branch around both thetransmitter and receiver containing a condenser and an inductance.

11. In a superposed-current telegraph, the

combination with the continuous-current receivers at a Way-station, ofan artificial shunt containing a condenser and an inductance in serieswith one another.

12. In a superposed-current telegraph, the combination with thecontinuous current transmitter and receiver apparatus at a Way-.station, of an artificial shunt taken around both the transmitterand'the receiver containing a condenser and inductance in series withone another.

13. The combination in a superposed-current telegraph with thecontinuous-current transmitter, of a shunt thereto containing acondenser and inductance and an artificial load-coil in the branch withthe transmitter for interposing artificial inductance when the key actsto shunt the branch or shunt containing the condenser.

' Signed at New York city, in the county of New York and State of NewYork, this 16th day of October, A. D. 1901.

- ALBERT C. CREIIORE.

\Vitnesses:

J. GALLWITZ, E. L. LAWLER:

